Valid coin acceptor for coin actuated apparatus

ABSTRACT

An improved coin acceptor mechanism employing an oscillator and a resonant circuit for detecting the electromagnetic effect of valid and invalid coins passing through a coil of the tuned circuit. A particular linear coil configuration provides a unique signature for each coin including at least one maximum and one minimum amplitude level of resonant circuit current. A comparator establishes at least two electrical signal amplitude windows representative of each valid coin signature. A logic circuit responds only to the coin falling within the two electrical signal amplitude windows for actuation. A novel coil design and assembly are enclosed.

BACKGROUND OF THE INVENTION

Coin acceptors for coin actuated machines have developed into a refinedart. In the past mechanical mechanisms have performed as many as seventests on a coin while it passes through an acceptor mechanism includingmeasuring its weight, diameter, resiliency, thickness, magneticproperties and freedom from a central hole.

More recently electromagnetic testing of coins has to a large degreesupplanted mechanical testing in electrically powered machines. We havefound however that the best electromagnetic testing acceptors stillreject valid but worn coins and accept invalid coins to an unacceptablelevel.

Typical electromagnetic testers employ an oscillator and a resonantcircuit including a single or double coil placed near a coin passage.The circuit detects a change in frequency in the resonant circuitresulting from the passage of a coin or other ferromagnetic materialthrough the coin passage. Certain such systems detect the amplitudechange of current in the resonant circuit. Typical prior art systems aredisclosed in the following patents:

    ______________________________________                                        3,317,016    Frequency shift detected                                         3,939,953    Vibrates coin                                                    3,741,363    uses 3 coils and a standard coin                                 2,642,974    coin passes through a coil                                       3,901,368    dual printed circuit type coils                                  3,870,137    dual frequency system                                            4,105,105    single acceptance window                                         4,108,105    single acceptance window for each                                             coin.                                                            ______________________________________                                    

Given these refinements, we have found that prior art systems still lacksufficient reliability. Moreover many require modification of orredesign of the coin actuated apparatus to accommodate the coinacceptor.

BRIEF DESCRIPTION OF THE INVENTION

We have discovered that it is possible employing a pair of coils ofimproved configuration to define more than one acceptance window foreach coin to be accepted and in doing so to improve the reliability inboth accepting valid coins and rejecting invalid ones. We have alsodiscovered that it is possible to integrate our improved reliabilitydevice into a package directly interchangeable with prior art acceptorsfor electrically operated coin machines without change. A vertical coinpassage is possible with our invention for minimum coin transit time andto minimize multiple coin blockage.

Our coils which embrace the coin passage include linear sections in thecoin passage region whereby the coin couples with two distinct linearcoil regions and produces a unique amplitude signature for that type ofcoin. The signature includes at least one maximum and one minimumamplitude level each of which must fall within acceptance levels.

Logic circuitry responds to the required sequence of maximum and minimumlevels to energize the coin mechanics acceptance solenoid. A counter isused to record the sequence and any deviation in amplitude resets thecounter, barring coin acceptance.

BRIEF DESCRIPTION OF THE DRAWING

This invention may be more clearly understood from the followingdetailed description and by reference to the drawing:

FIG. 1 is a perspective view of a physical embodiment of this invention;

FIG. 2 is an exploded view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a layout drawing for the schematic diagram FIGS. 11A-11G ofthis invention;

FIG. 5 is a generalized block diagram of this type of coin acceptor;

FIG. 6 is a block diagram of this invention;

FIGS. 7A-7D is a schematic diagram of a coin passing through thisinvention;

FIGS. 8A-10F are graphical presentations representing the operation ofthis invention;

FIGS. 11A-11G is an electrical schematic diagram of this invention;

FIG. 12 is an electrical schematic diagram of a power supply therefor;

FIGS. 13 and 14 are further graphical and timing diagrams illustratingthis invention.

DETAILED DESCRIPTION OF THE INVENTION

The need for a more effective coin acceptor for coin operated deviceshas been great as indicated above. This need also encompasses arequirement that an improved coin acceptor avoid the need of redesign ofthe hundreds of thousands of present, efficient and operating coinactuated vending machines. It is essential that such an improved coinacceptor be plug compatible with existing coin rejection devices suchthat the existing mechanical or electro mechanical device may be removedand directly replaced by improved coin acceptor. Therefore our inventioninvolves not only the development of the improved concept in circuitryfor providing a higher degree of acceptance of valid coins plus arejection of spurious or damaged coins.

Our concept involves such a plug-in equivalent device which is shown inFIGS. 1, 2 and 3. Our coin acceptor generally designated 10 comprises arectangle package including a frame or backing plate 11 and a coverplate 12 and extension jacketed four conductor cable 13 and a fourterminal plug 14 compatible with common existing coin rejectormechanisms. The package in this preferred embodiment is approximately 3inches by 2 and 1/2 inches by 1 inch designed to be located in therecess of coin actuated machines which employ commonly available coinrejectors. The assembly employs four printed circuit board type membersincluding a first coil plate 15, a second coil plate 16, a masterassembly circuit board 20, and an oscillator board not shown in FIG. 1but appearing in FIG. 2 and designated therein as circuit board 21. Anumber of the electronic components appear in FIG. 1 in a typicalinstallation employing discrete elements.

The coil boards 15 and 16 are separated by spacers 22 and 23 best seenin FIGS. 2 and 3. These spacers and the coil boards 15 and 16 define thecoil slot 24 therebetween. The coil slot 24 is partially open at itsfront side by reason of the angular cut off side 25 of the coil board 16in order to accommodate a coin gate which extends into the coil slot 24.The function of the coin gate is the same as in the case of mechanicalor electromechanical slug rejectors, namely to block the entrance ofspurious coins into the coin box and to discharge such invalid coins viaa discharge chute. The path of valid coins is indicated by the two coinsmarked V and the discharge path of an invalid coin is marked I.

Now referring specifically to FIG. 2 showing significantly more detailsof the coin acceptor of this invention one may see that a coin entranceopening 26 appears in the top of the assembly aligned with the normalpath of the coin to the coin gate controlled by solenoid unshown in thedrawing inasmuch as it is incorporated in the vending machine apparatusapart from the coin acceptance or slug rejection assembly.

The coin traverses the route through the coin acceptor 10 via theelongated slot 24 to the discharge opening and in doing so passesbetween a pair of planar coil sections 30 and 31 which preferably areproduced employing printed circuit techniques on the outer faces of thecoil plates 15 and 16. The spacer-guides 22 and 23 provide sufficientthickness between the two coil sections 30 and 31 to allow any coin ofthe appropriate thickness to pass therebetween and to changeelectromagnetic coupling between the two coils 30 and 31.

It must be noted that the coils 30 and 31 are elongated and extendingbroader than the coin path 24 and in particular have two generallylinear planar sections, the function of which is described below. A cointraversing the coin path 24 will pass through a region of close couplingwith the upper or linear sections 30A and 31A of the respective coils 30and 31 and will subsequently pass by the lower linear sections 30B and31B respectively. This passage arrangement is more clearly shown in FIG.7 in which the linear sections 30A and 30B appear in sequentiallocations as a coin travels through the coin path indicated by the arrowin FIG. 7A. The turns are connected in series in the preferredembodiment, however they may be tapped for use of different sized coinsor may include parallel sections if it is so desired.

Another feature of this invention is visible in FIG. 2. Overlying eachcoil 30 and 31 are respective magnetic shields 28 and 27 made uppreferbly of magnetic rubber tape which is bonded to the coils. We havefound that metal shields do cut down stray fields affecting theoperation but they also tend to reduce the field strength in the coinpassage. The use of magnetic rubber, permanent magnet particles embeddedin rubber served to retain the field in the coin passage and make theeffect of coin passage more pronounced and more repeatable. Any attemptto defeat the coin acceptor by magnetic means is thwarted by thismagnetic shield.

Again referring to FIG. 2 in conjunction with FIG. 7 it is apparent thatthere is an open section 30C and 31C which constitute a significantpercentage of the coin diameter measured in the direction of travel. Theimportance of the configuration of the coil is further described belowin connection with the operation of this invention.

Suffice it to say, FIGS. 1, 2 and 3 show a coin acceptor mechanism witha coin slot therethrough and coil means embracing the coin path and thenecessary electronic circuitry to process the required signal resultantfrom the coin passage and to determine whether the coin is a valid orinvalid.

The basic principle of operation of electromagnetic slug rejectors ofthe type including this invention is illustrated in FIG. 5 in which anoscillator 60 preferably controlled by crystal 61 provides a fixedfrequency output on lead 62 which in turn is amplified in bufferamplifier 63 to which a resonant circuit 64 is coupled. The resonantcircuit 64 comprises a capacitor 65 and a coil made up of a pair of setsof turns 66 and 70 connected preferably in series. The resonant circuit64 normally has a natural resonant frequency F1 significantly lower thanthat of the crystal 61 and provides a conventional bell shaped responsecurve centered on the frequency F1 in the absence of any perturbationsin the electromagnetic field encompassed by the coils or surrounding thecoils. The output of the resonant circuit 64 may be taken at terminal 71and introduced into a detector. If ferromagnetic or even nonmagnetic butconductive materials are introduced into the field of the coil 66 and 70the characteristic output curve is changed in particular by a shift ofthe bell shape curve from the frequency F1 to a different frequencyshown in FIG. 5 as F2. Typical prior art systems look for the frequencyshift Delta F and make the determination in the detector as shown inFIG. 5 whether a coin is valid or invalid depending upon the value ofDelta F.

We have found that while a coin detector based upon the principle andsystem of FIG. 5 in theory is operative it is not useful per se in thatit lacks the necessary slug rejecting capability and also tends toreject good but worn coins to the frustration of the vending machineoperator in the first case or the patron in the second case.

Our invention is illustrated in FIG. 6 in which identical referencednumerals are employed where appropriate to show the similarity wheresimilarity exists. Again a crystal controlled oscillator 60, bufferamplifier 63 and a resonant circuit 64 made up of a pair of turns 66Aand 70A and a capacitor 65A are used. A detector 71 is for purpose ofconvenience incorporated in the buffer amplifier module but functionallyis as described below. Beyond the detector 71 however a plurality oflevel discriminators are employed, specifically, four different leveldiscriminators identified as C-1, C-2, C-3, and C-4 are employed. Leveldetectors C-1 and C-2 define a first amplitude window while C-3 and C-4define a second amplitude window. The output of the level discriminatorsand comparators 72 is applied to a sequence counter 74 capable ofcounting a plurality of sequences the preferred number being three. Thesequence counter 74 may be a simple three stage counter with a resetinput. The sequence counter is operative when a count of three isreached to provide an enabling pulse to a gate timer driver 75 whichoperates the solenoid 76 of a coin gate positioned in the path of thecoin to direct the coin either to the valid coin bin or to the invalidcoin discharge slot.

Referring again to FIG. 7 in conjunction with FIG. 6, it may be seenthat the coil employed in this invention is not simply a multi-layeredcoil or even a flat helically wound coil of continuously curveconductors as in the past. Instead the coil is elongated in a directiontransverse to the direction of passage of coins and includes a pair ofstraight sections each having a width W greater than the transversedimension of the valid coin to be accepted. The coils also include asignificant central area free of winding which must be passed by thecoin 100 in traveling through the coin passage.

It is apparent by reference to FIGS. 7A, 7B, 7C, and 7D that the cointraverses three distinct regions in passing through the coils. It isalso apparent by reference to FIG. 7D, that the length L through whichthe coin travels is greater than the transverse dimensions d of thecoin. The central opening area is approximately 20% of the value d inthe optimum coil design as we have found by experimentation. Typicaldimensions of the coils 30 and 31 for use with a U.S. quarter or theSusan B. Anthony Dollar to be as follows:

    ______________________________________                                        Number of series of turns                                                                            2                                                      locations              opposed                                                Number of turns per section                                                                          21                                                     Straight section length W                                                                            1.2 in.                                                Central open area path length 1                                                                      0.2 in.                                                Total path length through coil                                                                       1 in. or more                                          Max coin diameter      approx 1 in.                                           ______________________________________                                    

The same coils may be used with smaller coins but the straight length Wand the path length L have been found by us to provide effective andreliable acceptance of valid coins and rejection of invalid ones whenthe above criteria are met.

The effect of the passage of a coin through the passage 24 of FIGS. 1and 2 is shown graphically in FIG. 8 in which the same letters are usedto represent set of conditions. As shown in FIG. 8A, the bell shapedcurve centered around the frequency f1 is apparent and at a lowerfrequency than the crystal frequency f0. As the coin 100 of FIG. 7Bbegins to pass the coil 30 the response curve remains symetrical buttends to move in the direction of the crystal frequency f0 and at sometime in its passage corresponding to FIG. 7c the peak will pass throughthe crystal frequency p0 and at sometime later the peak will move beyondf0 to the right.

Prior art systems have characteristically employed frequency sensitivenetworks, filters and the like and have attempted to provide aregistration of valid or invalid coins based upon the value of p1. Suchsystems have characteristically attempted to maintain the coin in afixed position long enough to establish a value f1. Other prior artsystems have employed bridge circuitry employing a "standard" coin as areference and detected bridge unbalance as an indication of invalidcoins. The configuration of the coils disclosed herein, by way ofcontrast, provides a characteristic response curve as shown in FIG. 9Awith two peaks separated by a valley. The frequencies of the peaks fx1and fx2 are not critical nor are they detected.

FIG. 9B shows the criteria for selection of a valid coin in accordancewith this invention, namely that there be at least one maximum and oneminimum as defined by a pair of amplitude windows, 1-2 and 3-4. Theseamplitude windows are established by amplitude threshold devices whichare operative over the frequency range including fx1 and fx2. The use ofthese amplitude windows is best illustrated in FIG. 9C.

Through the use of four comparators, the correct logic for theevaluation of a valid coin may be carried out. Employing a series ofcomparators, identified in FIG. 9C as C-1, C-2, C-3 and C-4, thefollowing sequence for a valid coin occurs:

When a coin of the correct electromagnetic properties passes through thecoin passage to allow the window 1-2 to be entered, a comparatorcorresponding to the level C-1 causes the counter to be advanced to alevel 1, represented by an encircled 1 in FIG. 9 C.

If the characteristic of the coin matches the characteristic shownsufficiently to drop below the window entrance level C3, the counter isadvanced to the count of 2 as represented by the 2 encircled in FIG. 9C.

Again following the curve further, as the window 1-2 is again entered,the comparator advances the counter to the count of 3. This level ofcorrespondence of the signature of a valid coin, has been found to besufficient to accept virtually all valid and reject virtually allinvalid coins. We have thus determined that using a three stagecomparator is sufficient and does not require further qualification ofthe coin.

Conceivably, and within the scope of this invention, a fourth test couldeasily be employed and is indicated in the drawing by a dashed circled 4as the curve again falls below the level 3 into the 3-4 window. Thecomparators C2 and C4 are similarly connected to the counter, howeverthese comparators are coupled to the reset input of the counter to resetthe counter to 0 rather than to advance it.

The effect of the reset capability in the comparator is best illustratedin connection with FIG. 10 showing six typical invalid coincharacteristics. By carefully tracing the curves of FIG. 10 using thelogic as described in connection with FIG. 9C, one can see that under nocircumstances, as illustrated by each of these six varients does thecounter reach a count of 3.

In the waveforms of FIGS. 10C and 10E, a maximum count of 2 isregistered while in the remaining curves A, B, D and F the counter neveradvances beyond a count of 1.

The operative circuit which carries out this invention for multicoinoperation may be seen in FIG. 11 which is made up of seven sheetsarranged as shown in FIG. 4. As the system appears in FIG. 11, theoscillator 60 appears at the upper left of the drawing in FIG. 11A andis shown with its associated crystal 61. Connected through a pair ofplug and jack combinations to the oscillator 60 is the resonant circuit64 with its two coil sections 66A and 70A. The output of the oscillatoramplifier 60 is coupled over lead 80 through capacitor 81 to detector71. The detected output is introduced on to line 82 which feeds thedetected characteristic of the coin to four (or more) similar circuits72A, B, C and D, each including comparators selected to establish therequired windows for each of the coins desired to be detected. Thecomparators, in this case four in number are four identical integratedcircuits having four comparator circuits each to make the C-1 throughC-4 comparisons required as described above. The integrated circuits arepreferably type IC 339.

The first comparator 72A is adjusted to establish the windows for avalid Susan B. Anthony dollar. Its four output level values whenoutputed are introduced into an NAND gate logic network 73 whichresponds to the C-1, C-3 sequence to advance the counter 74 via line 83.The same logic network responds to either a C-2 or a C-4 level to resetthe counter 74 over lead 84. FIG. 13 illustrates the timing sequence ofcomparators C1 and C3.

Whenever the counter 74 reaches a count of 3 it triggers four "wait toopen" timers 75A,B,C, and D which have a delay such as 15 milliseconds,sufficient to allow the coin to complete its passage through the coinacceptor. This is illustrated in FIG. 14. The timers 75A-D are triggeredover lead 85. These timers 75 are all connected via lead 86 and an ORgate 90 to a "hold open" timer 75E which in turn for a period such as 30to 35 milliseconds applies an operating signal over lead 91 to theacceptance gate driver circuit 92 which in turn supplies solenoidoperating power to the acceptance gate winding. Actuation of the circuit92 under the conditions described above results in the Susan B. Anthonycoin being accepted. An additional output on lead 93 is provided for usein counting the number of coins deposited for change making calculationsor accounting purposes.

The comparators 72 are replicated as described above and the logicnetworks as well for each coin to be accepted. The operation of each ofthese replicated circuits is the same as described above for the SusanB. Anthony dollar. Given this replication, each coin is tested againstthe window combinations for each particular coin and if the criteria forany one is met, the acceptance gate will open.

Employing this invention, experimental apparatus exposed to a largenumber of valid coins plus an equally large number of foreign and noncoin articles of the type commonly accepted by existing coin rejectorsgave virtual 100% acceptance of valid coins and virtual 100% rejectionof the invalid ones.

We have also found that the windows used for establishing acceptance orrejection of a coin may be narrowed or widened for the particularapplication. As an example, the window height for most applications isin the order of 5 volts where the maximum amplitude is in the order of20 volts. We can narrow the window to in the order of 1 volt in order toaccept coins which are virtually identical. This can, for example, beused to discriminate between uncirculated and circulated coins of thesame denomination. A further application based upon this feature is thedetection of coins having less than standard purity. We have found thatcoins having less than 1% deviation from established standards may bedetected. This is particularly valuable in detecting bogus coins or barsof precious metals.

The foregoing detailed description is intended to disclose the best modeof carrying out the invention as known by the inventors at the time offiling of this application but is not to be in any respect a limitationon the scope of their invention. Rather, the invention shall bedetermined as defined by the following claims including theirequivalents.

What is claimed is:
 1. A coin acceptor comprisinga frame assemblydefining a package of size and shape interchangeable withelectromechanical coin acceptors for coin actuated machines; said frameassembly further defining a coin passage entrance and exit through saidpackage; a pair of spaced generally planar members for defining acontinuous coin passage therebetween; said generally planar members eachmounting a series of conductive turns for establishing anelectromagnetic field in the region of said coin passage; said series ofconductive turns including at least one generally straight length ofturns having a straight length at least equal to the major transversedimension of a coin to be accepted and separated from the remainingportion of said series of turns by a region free from turns; meanscoupling electric current to said series of turns; means for detectingchanges in the current in said field as a function of the passage ofcoins through said passage; logic means for detecting at least onemaximum and one minimum level of current during the passage of a cointhrough said passage; means for comparing the maximum and minimumcurrent levels with a predetermined maximum and minimum value; and meansfor applying enabling input to said machine responsive to the output ofsaid comparator means.
 2. The combination in accordance with claim 1wherein said planar members comprise a pair of printed circuit boardsdefining said coin passage therebetween and having said series ofconductive turns on the opposite faces thereof.
 3. The combination inaccordance with claim 2 wherein said series of turns on said planarmembers are connected in series.
 4. The combination in accordance withclaim 1 including edge spacers between said planar members for definingsaid coin passage in a lateral direction to be restricted to thestraight lengths of said conductive turns.
 5. The combination inaccordance with claim 1 wherein said apparatus defines a straightuninterrupted coin path through said coin acceptor.
 6. A coin acceptorcomprisingan oscillator for establishing a oscillatory signal; aresonant circuit for controlling the frequency of said oscillator, saidresonant circuit comprising a pair of series of inductive turns and acapacitor; dual means defining a coin passage therebetween; said dualmeans mounting respective pairs of series of inductive turns to beelectromagnetically coupled to said coin passage; said series ofinductive turns including linear portions coinciding with said coinpassage; means responsive to the change in electromagnetic couplingbetween said pairs of inductive turns due to a coin passage therebetweenfor registering a valid or invalid coin; said responsive meanscomprising a series of amplitude comparators for comparing the amplitudeof the current in said inductive circuit as a function of passage of acoin; logic means coupled to said amplitude comparators for registeringa valid coin responsive to a sequence of at least one predeterminedmaximum and sequential minimum amplitude being detected during coinpassage.
 7. The combination in accordance with claim 6 wherein saidcomparators comprise at least four comparators two for maximum amplitudelevel and two for minimum amplitude levels.
 8. The combination inaccordance with claim 7 wherein said maximum comparators include a firstone for establishing a threshold value and the second for establishing amaximum level.
 9. The combination in accordance with claim 8 whereinsaid logic means is responsive to said first comparator for registeringan indicator of valid coin and responsive to said second maximumcomparator for registering an invalid coin.
 10. The combination inaccordance with claim 9 including timing means responsive to thedetection of said first maximum for enabling the detection of said firstminimum whereby a valid coin will only be registered if a minimum of atleast a predetermined level follows a maximum of a predetermined level.11. The combination in accordance with claim 8 wherein said logic meansis responsive to said first minimum comparator for registering anindication of a valid coin and responsive to said second minimumcomparator for registering an invalid coin.
 12. The combination inaccordance with claim 7 wherein said logic means comprises a series ofgates and a counter wherein said counter is advanced by pulses passingsaid gates corresponding to the maximum and minimum criteria.
 13. Thecombination in accordance with claim 12 including means responsive to apredetermined count in said counter for registering a valid coin. 14.The combination in accordance with claim 12 including means responsiveto exceeding said second maximum comparator or said second minimumcomparator for resetting said counter.
 15. The combination in accordancewith claim 12 including means responsive to said counter reaching saidpredetermined count for registering a valid coin.
 16. The combination inaccordance with claim 15 including means for resetting said counterresponsive for registering a valid coin.
 17. The combination inaccordance with claim 12 including logic means coupled to said firstthreshold comparator for registering a second passage of amplitude levelpast said threshold, said logic means coupled to said counter foradvancing said counter upon the detection of the amplitude levelreaching said first threshold for a second time.
 18. The combination inaccordance with claim 17 wherein said counter is responsive to a countof 3 for registering a valid coin.
 19. The combination in accordancewith claim 17 wherein said logic means is responsive to the exceeding ofsaid second maximum comparator for resetting said comparator.